first dwc grow 400w

Used to grow in coco but moved states and gave up. Recently seen a sale at at my local hydro shop and decided to try again. My current setup

18gl dwc tote (holds about 15gl)
400w Apollo dimmable system.
General Hydro complete floraseries
Can't figure out what size tent to buy or fan so haven't gotten one yet.

Plants are at three days old bagseed, using 2ml\gl of rapid start, 1ml\gl of Floramicro, Flora grow, and florabloom and 4ml or floracious blend.
Ph is roughly at 6.0 and ecm is unknown but a ppm and ph meter is next on my buying list. Testing a 3gl plastic barrel that was used for cheese balls lmfao. Have a 1inch net pot in the lid and I ain't using a Rockwol cube either for it

Ignore the ugly Mylar job lol and my temporary setup until I get a tent and fan.

Anyone have any pointers or tips?

Moved light about 1' away from plants and they still seem to be stretching slightly. Roots still havnt popped through the net pot but the experiment is already 3 separate roots into the water and is still on it's first true leaves lol?